4aS,8aS-1-benzoyl-7-oxodecahydroquinoline has been prepared, among other compounds by the hydroxylating action of Sporotrichium sulfurescens on the substrate 4aS,8aS-1-benzoyldecahydroquinoline followed by CrO.sub.3 oxidation. LiAlH.sub.4 reduction of the mold metabolic product gave 4aS,8aS-1-benzyl-7-hydroxydecahydroquinoline. Debenzylation with hydrogen using a palladium-on-carbon catalyst produced 4aS,8aS-7-hydroxydecahydroquinoline. The corresponding 4aR,8aR-derivative was not found in the fermentation when the 4aS,8aS starting material was used. The above chemistry is outlined in a paper by Johnson et al., J. Org. Chem., 33, 3207 (1968) where 4aS,8aS-7-oxodecahydroquinoline is compound no. 26 (named as a quinolin-7-one).
Momose and coworkers at Osaka U. have prepared a series of octahydro-7(1H)-quinolines. Paper no. I appearing in Chem. Pharm. Bull., 25, 1436 (1977) discusses the results of hydrogenating 7-hydroxyquinoline over 5% Rh/Al.sub.2 O.sub.3. N-benzylation via the N-benzoyl derivative gave four products, a cis-dl-mixture and a trans-dl-mixture. The individual racemates were obtained by chromatography. The preparation of trans(.+-.)-7.beta.-hydroxydecahydroquinoline (XVIII) from trans-(.+-.)-7-oxodecahydroquinoline (XIa) was also outlined. Paper no. II (ibid 1797) prepares cis-(.+-.)-7-oxodecahydroquinoline by two different procedures. Paper no. III (ibid 26, 620 (1978)] discusses the isomerization of the cis-(.+-.) and trans-(.+-.)-7-oxodecahydroquinolines.
Pearson et al J.C.S., Perkin Transactions, I 619 (1983) also discloses the preparation of cis-(.+-.)-7-oxodecahydroquinolines carrying a substituent at 4a.
It is an object of this invention to provide an improved synthetic route to trans-(.+-.)-7-oxdecahydroquinoline which route is free from the isomer problems which beset the prior art synthetic procedures.